Friday, July 2, 2010

Friend of the Week: Hover Fly

Hover Fly or Flower Fly (many different species) – Order Syrphidae

Why a friend: Larvae of the hover fly eat crop-damaging and disease-transmitting insects. There are many species of hover fly throughout the world. Adults are easily attracted to where a grower needs them. Hover fly larvae consume as many and sometimes more pests than ladybird beetle larvae. Adult hover flies help pollinate plants as they feed on the nectar and pollen in the flowers.

Predator of: Aphids, small caterpillars, thrips, scales, and other small soft-bodies insects

Life Cycle: Adults lay eggs on the undersides of leaves of crops that have pests present. Eggs hatch and the larvae begin feeding. Larvae pupate into adults in 10-30 days, depending upon the temperature. These beneficial insects overwinter in colder climates as pupae in the soil or on crop debris. In warmer climates there will be adults and larvae present all year. Pupation will occur at 30-33 days during the cooler temperatures of winter in southern regions.

How to Attract: Native populations of hover flies are easily attracted to pest populations with well-positioned insectaries. An insectary is a garden planted to attract beneficial insects. Insectaries can be planted with white alyssum, yarrow, cilantro (let it go to flower), parsley (let it go to flower), basil (let it go to flower), anything in the carrot family, clover, nasturtium, buckwheat, ammi, golden tuft, dill, cosmos, mizuna, hairy vetch, and chamomile. Insectaries planted in the immediate area of the target crop will be the most beneficial. Plant an insectary outside the open end wall of a hoophouse. Adults will fly into the hoophouse to lay eggs on the crop plants. Insectaries can also be placed in strips between fields, put into a planting plan within the field, or planted into containers. The containers allow them to be mobile so you can place them just about anywhere you need them. We recommend planting any of the following and letting them go to flower in your insectary planting: Beneficial Insect Attractant Mix (#1832), Colorado Yarrow (#1338), Genovese Basil (#911G), Blue Spice Basil (#181), Mrs. Burns’ Lemon Basil (#774), Common Chamomile (#914), Santo Cilantro (#2928), Bouquet Dill (#920G), Grosfruchtiger Leaf Fennel (#2395), Forest Green Parsley (#529), White Dill Ammi (#1034), Jewel Mix Nasturtium (#1420), Mammoth Red Clover (#980G).

How to Identify: These true flies (in the Order Diptera) float over crops and duff (thick layers of organic matter on soil surface) like a kite, seemingly not moving. They are a rare exception in the insect world in that they can fly backwards. They have one set of wings, unlike the insects that their body color mimics (wasps and bees in the Order Hymenoptera) who have two sets of wings. This mimicry is thought to deter predators from eating the hover fly because of potential stinging. Hover fly larvae are not easily found, even for entomologists. They resemble a slug or worm that is about 4-8mm long and can be off-white or light green in color. Adult populations are easy to spot when there are aphids or other soft-bodied pests present. They hover over the crop looking for a good place to lay eggs, and will land and feed on the nectar and pollen of flowers nearby.

Further Resources

View all Johnny's seed varieties that Attract Beneficial Insects »

To learn more, visit our Grower's Library for articles on Attracting & Putting Beneficial Insects to Work »


1 comment:

Pure-n-Simple said...

I love these beneficial insects and will grow what ever draw them in, especially if they wipe out all the not so beneficial ones.